get_member_cmt

get comment of a member
     id            - structure type ID
     member_offset - member offset. The offset can be
                     any offset in the member. For example,
                     is a member is 4 bytes long and starts
                     at offset 2, then 2, 3, 4, 5 denote
                     the same structure member.
     repeatable   - 1: get repeatable comment
                    0: get regular comment
returns: 0 if bad structure type ID is passed
           or no such member in the structure
         otherwise returns comment of the specified member.

string get_member_cmt(long id, long member_offset, long repeatable);